1. Technical Field
This invention is related to the field of printing, and in particular to printers with a paper path and paper detection sensors on the paper path.
2. Description of Related Art
Generally, setting or resetting of some parts or operational programming of a printer is necessary before a sheet is fed through the printer in order to correctly determine jamming of the sheet or printing errors in the apparatus. For this setting of the imaging apparatus, input of information about the length and/or width of the sheet to be fed is required in advance.
Recently, there are more demands to print texts or images on irregular-sized sheets, especially on long-sized sheets (hereinafter referred to as banner sheets) to make a signboard or others for instance.
In case where the size of sheets is irregular, the user usually needs to measure the length and width of one of the sheets in a sheet-feeding tray provided in the apparatus and inputs the dimensions using a keyboard on the apparatus. Actually this manual work is troublesome and is often accompanied with measurement error of the length and width. Further, this work may need, for example, a scale, a long table and the space for the measurement. Besides, there may be sometimes a long sheet whose length is difficult to measure manually and precisely.
Here, an irregular-sized sheet is intended to mean at least one of whose length and width are not the length and width of the regular-sized sheet such as of the A4 size, the letter size and the legal size, while a long-sized sheet is intended to mean a sheet at least whose length in the sheet feeding direction in the apparatus is longer than regular sized-sheets.
Conventionally, an image forming apparatus, which has a measuring system for the regular-sized sheets, has been disclosed in U.S. Pat. No. 7,164,881, for example. This image forming apparatus selects types of sheets such as an A4 size sheet, a letter size sheet and a legal size sheet by measurement of the length of the sheet while the sheet is being fed in the apparatus. To be more specific, data pertaining to sheet length in the sheet feeding direction for regular-sized sheets have been installed in the imaging apparatus in advance. The sheet length is measured while the sheet is being fed in the apparatus, and the acquired dimensions are compared with the stored data of the sheet length to find the regular-sized sheet corresponding to the obtained dimension Then, one of the regular-sized sheets is selected as default media for future operations.
Needless to say that this type of apparatus devised for the regular-sized sheets is not available for irregular-sized sheet especially for long-sized sheets, since the image forming apparatus has no idea about the dimensional information of the irregular paper in advance.